Patients receive geldanamycin analogue (AAG) IV over 1-6 hours once daily on days 1, 4, 15, and 18. Courses repeat every 4 weeks in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients receive escalating doses of AAG until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity. Once the MTD is determined, an additional 10 patients are treated at the MTD.